International row likely after revelations of breach that could have given NSA and GCHQ the power to monitor a large portion of world’s cellular communications Sim card Gemalto, the company targeted by the spy agencies, produces 2bn sim cards per year for clients including AT&T, Sprint, T-Mobile and Verizon. Photograph: Kimmo Mntyl /Rex Features Share viaShare on Google+ American and British spies hacked into the world’s largest sim card manufacturer in a move that gave them unfettered access to billions of cellphones around the globe and looks set to spark another international row into overreach by espionage agencies. The National Security Agency (NSA) and its British equivalent GCHQ hacked into Gemalto, a Netherlands sim card manufacturer, stealing encryption keys that allowed them to secretly monitor both voice calls and data, according to documents newly released by NSA whistleblower Edward Snowden. The breach, revealed in documents provided to The In...